Aircraft combustion engines that burn hydrocarbon fuels are limited in their flight altitude because at high altitudes, there is insufficient oxygen to sustain combustion. Aircraft that operate on combustion engines are also limited in the total time and distance that can be achieved between landings, due to the weight and quantity of fuel that they must transport. Aircraft that do not rely on combustion engines can achieve higher flight altitude, as well as longer flight times, than aircraft that rely on combustion engines. Some high-altitude airplanes have been powered by solar power, but sunlight has low intensity under the best circumstances and is unavailable at night. For example, the HELIOS Prototype is a solar powered aircraft developed by NASA and AeroVironment Inc., of California, as part of the Environmental Research Aircraft and Sensor Technology (ERAST) program. However, limitations have been encountered with the operation of HELIOS and other solar-powered aircraft.
Solar intensity is especially low during winter months in higher latitudes. The transmission of power beams, or “power beaming”, is one solution that was developed to alleviate the problem of low-intensity regions of solar power. The concept of power beaming goes back at least as far as the famous scientist Nikola Tesla (1856-1943). There is a large body of literature regarding power beaming, which is also referred to at times as “wireless power transmission.” Power beaming includes a set of technologies that transmit large, non-destructive amounts of power from some source to some receiver via electromagnetic waves, e.g. microwaves or light. Power beaming can provide the equivalent energy levels of high-intensity sunlight with nearly 100% duty cycle.
Power beaming has been used to demonstrate the feasibility of use in small aircraft. However, power beaming from a single beam power source to a single user node such as a small aircraft, has limited usefulness. The user node is constrained to flight within the direct line-of-sight of the source node, and the reliability of the user node or aircraft is dependent on the reliability of the power source or source node. Singular source nodes do not have the ability to handoff user nodes from one source to the next to improve flight reliability of the user aircraft node, and to enable a user aircraft node to receive sufficient power to sustain flights of long-distance or long-duration.
A single source may be configured with power beam characteristics that are incompatible with a particular aircraft—e.g., the power beam may be too powerful or too weak. Since there is not a uniform standard for power beaming, interoperability becomes difficult, reducing the value of each type of aircraft and each type of source node.
Current ground-based power beam source nodes encounter additional obstacles to power transmission. Atmospheric obstacles such as clouds or turbulence interfere with the power transmissions by scattering light. Since some user nodes receive the power via arrays of photovoltaic cells that are limited in area, much of the transmitted power becomes unfocused due to such spreading and is lost.
Maintaining airborne surveillance is another challenge that cannot be effectively achieved using combustion propulsion, as political and military factors reduce airborne intelligence, surveillance and reconnaissance (ISR) below 100 thousand feet. Higher altitude surveillance is desirable because of the ability to acquire a larger visible area ratio as the altitude of the surveillance aircraft increases. Strong winds at extreme altitudes cause conventional airships to consume a prohibitive amount of power just for holding the airship in a fixed position, thus making fixed wing aircraft more desirable.
Providing for the needs and capabilities of multiple user nodes, source nodes, and relays to create a distributed power beaming system is a complex undertaking. Such a system is unable to function properly without interoperability and the ability to represent various attributes and interactions between the nodes of the power-beaming network.
Applying Network Centric Operations (NCO) concepts and expertise to directed energy weapons and power beaming, the present invention addresses a need to make directed energy platforms more network-compatible.
There is a need for a power beaming network architecture to enable each beam-powered aircraft to be served by one or more power beams in various locations to accomplish high-altitude flights of extreme duration. There is also a need for a distributed network of power beaming source nodes to allow the source nodes to be built in smaller sizes in order to reduce the cost per unit of power.